A group of investigators will study various parameters of the cell membrane, eventually hoping to gain an understanding of mechanisms of development, and to clarify some aspects of malignant and other abnormal growth. The group, which includes geneticists, protein chemists, immunologists, virologists and electron microscopists, will collaboratively study several topics ranging from the properties of H2 transplantation antigens and embryonic antigens, to an analysis of cell membrane during the development of slime molds, and interaction of viruses with cell membranes. Studies of cell contacts and cell movement will also be carried out in normal and transformed cells.